I read and I don't think anyone answered your last question directly.
I think that CFM is much more important than the speed of the fan,
when used over a quality heatsink, all I care about is the amount of air the fan will deliver to the sink. There comes a point when too high speed is just too obnoxious to tolerate. A few fans a just plain Way too loud.
I got sucked into the whole Orb obsesion last month, DO NOT BUY THIS COOLER. I had the Chrome Orb, my T-bird was 59 Celcius! 59!!
Put on a GlobalWin FOP32-1 temps are now at around 40-44 degrees Celcius. The Orb has become my most fancy paperweight!